Abstarct Interface

[Manoj Agnihotri]

Can anybody explain about abstract interfaces ?
What is the significance of these interfaces ?

[Christophe Verré]

Let's clear up some Java terminology first There is no "abstract interfaces" in Java. There are interfaces, and abstract classes.

[Manoj Agnihotri]

abstract interface example
{
  void showMessage();  
}

abstract keyword is allowed to use like this.
I want to know if it is allowed then what's the use of this ?

[Christophe Verré]

abstract interface example

Nice But in Java, this is still called an interface. Not an abstract interface An interface is by definition purely abstract, because it cannot do anything concretely. This declaration is redundant, so we usually (always?) omit the "abstract" keyword to define an interface.

By the way, your interface could also be written like this :

abstract interface example
{
  public abstract void showMessage(); 
}

but people usually write it like this :

interface example
{
  void showMessage(); 
}

[sachin verma]

Yes you can use this before any interface like you did.

An interface is implicitly abstract so there is no need to declare it abstract.
As interface variables are all implicitly public static final whether you declare it or not.
So it would create redundancy to use abstract in interface declaration and public static final in constant declaration.
[ April 30, 2008: Message edited by: sachin verma ]

[Manoj Agnihotri]

Thanks ..